In the paper “A White-Box DES Implementation for DRM Applications” by S. Chow, et al. a white-box implementation of the Data Encryption Standard (DES) is presented (referred to as ‘Chow’ below and incorporated by reference herein). A white-box implementation is a cryptographic implementation designed to withstand an attack in the white-box context. In the white-box context, the attacker has total visibility into software implementation and execution. Nevertheless, even so the white-box implementation aims to prevent the extraction of secret keys from the program.
Chow forms an implementation of DES that consists entirely of table look-up operations. Through several intermediate methods the normal cipher is transformed to an implementation in this form. Input and output encodings are used to protect all these tables.